California-Modified Style Split-Spoon Samplers

SPT is an in-situ dynamic penetration test designed to provide information on the geotechnical engineering properties of soil and is the most widely used in-situ soil characterization test in the industry.

The main purpose of SPT is to provide an indication of the relative density of granular deposits, such as sands, silts, gravel, clay containing sand or gravel, and rock from which it is virtually impossible to obtain undisturbed samples. The test is most useful in soil types with fine-grained sands, however, it can be used in a wide variety of unconsolidated lithologies.

Application:
The SPT test involves attaching a standard cylindrical sampler, split-spoon sampler, to drill rods suitable for geotechnical testing and sampling. The samplers can be advanced to deeper depths through hollowstem auger borings or direct push tooling. The sampler is then driven into the ground with a geotechnical hammer and the number of blows needed for the tube to penetrate each 150mm (6") up to a depth of 450mm ( 18") is recorded. The sum of the number of blows reqired for the second and third 6" of penetration is termed the "standard penetration resistance," or the "N-Value". The blow count provides an indication of the density of the ground and it is used in many geotechnical engineering formulas.